The present invention generally relates to copying apparatuses and more particularly, to a copying apparatus in which copy paper sheets ejected out of an apparatus housing of the copying apparatus are received so as to be refed from a sheet feeding portion of the copying apparatus into the apparatus housing.
Generally, in order to perform duplex copying or composite copying in copying apparatuses, one copy paper sheet is required to be fed twice. To this end, various copying apparatuses have been proposed. For example, in order to simplify operations of duplex copying in a copying apparatus having a U-shaped sheet feeding passage, U.S. Pat. No. 4,017,173 proposes a sheet refeeding device in which an upper sheet cassette movable between a sheet ejecting portion and a sheet feeding portion is displaced, at the time of copying onto a front surface of a copy paper sheet, to the sheet ejecting potion so as to recieve the copy paper sheet and is displaced, at the time of copying onto a back surface of the copy paper sheet, to the sheet feeding portion so as to refeed the copy paper sheet.
Meanwhile, Japanese Patent Laid-Open Publication No. 134659/1983 discloses a sheet refeeding device for a copying apparatus having a straight pass type sheet feeding passage, in which a sheet cassette having a sheet receiving opening and a sheet feeding opening is detachably mounted on a sheet ejecting portion and a sheet feeding portion upon turnover of front and back surfaces of copy paper sheets.
However, in the known sheet refeeding devices referred to above, since the upper sheet cassette or the sheet cassette itself is displaced from the sheet ejecting portion to the sheet feeding portion, another copy receiving tray is required to be additionally provided at the sheet ejecting portion at the time of copying onto the back surfaces of the copy paper sheets. Furthermore, the known sheet refeeing devices have such a drawback that the upper sheet cassette and the sheet cassette are designed for exclusive use in the known copying apparatuses, respectively and therefore, cannot be provided, as options, in other existing copying apparatuses having no sheet refeeding device.